The invention relates to a drive and metering device for an injection device for administering a liquid product, particularly a medicine such as insulin. A product dose to be administered can be set with the drive and metering device and preferably can be discharged by means of multiple individual discharges, wherein the metering and discharging steps can be repeated multiple times. The invention thus also relates to an injection device having such a drive and metering device. In particular, the drive and metering device has a mechanically acting dose display, on which the dose to be administered can be read.
From the prior art, particularly WO 2009/105909A1, an injection device is known that has a housing in which a dose display sleeve is arranged. A metering button that can be rotated and is axially fixed relative to the housing is arranged at the rear end of the housing. By rotating the metering button, the dosage display drum is screwed along a thread formed by the housing. The set product dose can be read through a window of the housing. By actuating an actuating button, likewise at the rear end of the housing, a preloaded drive spring is released, which drives a piston rod for discharging the product and simultaneously turns back the dose display drum proportionally to the amount of discharged product, the dose values displayed in the window being counted down or running back in the direction of the zero-dose value.
In case of an interruption of the dose discharge, this device advantageously allows the amount of product yet to be discharged to be read in the window. The user of the injection device can recognize the end of product discharging in that the dose indicator stops and the value zero can be read in the window.
There are patients, however, who cannot securely perceive the signaling by the lack of a movement. Instead they require active signaling.